In ongoing evolution in the game of golf, along with a shift to lighter weight shafts there has been increased interest in custom-matching golf clubs to individual golfers in recognition of the differences that characterize individual golfers such as height, weight, strength, firmness of grip, path and velocity of swing, etc., and the differences in golf clubs such as total length, total weight, weight distribution considering head weight, shaft weight and grip weight, along with other variables such as shaft stiffness and related resonances. The overall result of these variables determines how a particular club “feels” to that particular golfer.
For club-matching purposes, the golf industry developed a rating known as “swing-weight”, based on balance measurements made on the club about a fulcrum point usually twelve or fourteen inches from the club cap, characterizing the club on a scale of 77 increments with letters A-G followed by numerals 1-10. Industry standards are D0 or D1 for men and C5 to C7 for women. In another rating system, the MOI (moment of inertia: in physics the product of mass and distance from the axis of rotation) is expressed in terms of total club weight and distance from the center of gravity (balance point) to an arbitrary axis of rotation, usually taken at the club cap end, but suggested by the present inventor as more realistic if taken at an outside point, e.g. twelve inches beyond the cap.
Many golfers including pros are not fully satisfied with the existing rating systems and regard them as approximate guidelines at best, so there is an unfulfilled need for after-market accessories that enable even initially “matched” golf clubs to be fine-tuned to more closely match the golfer's individual physique and needs for improved performance.